Regensburg 2010 – scientific programme

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DS: Fachverband Dünne Schichten

DS 29: Poster: Molecular Spintronics, Biomolecular and Functional Organic Layers, Organic Electronics and Photovoltaics, Plasmonics and Nanophotonics, Organic Thin Films, Nanoengineered Thin Films, Thin Film Characterisation,

DS 29.44: Poster

Wednesday, March 24, 2010, 15:00–17:30, Poster A

Sb-Bi thin films investigated by structural and optical methods — •Anja König, Peter Zalden, Gunnar Bruns, and Matthias Wuttig — I. Physikalisches Institut (IA), RWTH Aachen, 52056 Aachen, Germany

Phase-change materials (PCMs) offer a significant optical contrast as well as a distinct difference in electronic resistivity between their amorphous and crystalline state. Moreover, they can be rapidly switched between these states thus making them a promising material for non-volatile electronic memories. The crystalline phase of these materials shows a large optical dielectric constant, which is explained in terms of a large dynamic charge, also known as resonant bonding. A map for PCMs has been developed on the basis of a fundamental understanding of the bonding characteristics [1]. However, stoichiometric trends in terms of the dynamic charge and its origin are yet to be investigated.

Therefore, in this study binary Sb-Bi thin films were evaporated in varying stoichiometry and examined structurally (XRD, XRR) and optically (ellipsometry). The binary Sb-Bi system was chosen since these alloys provide three p-electrons per atom throughout, thus fulfilling the prerequisite to be accurately described by the map in every stoichiometry. Additionally, they show a stoichiometric trend regarding the magnitude of the rhombohedral distortion, which is a well know property of some phase-change materials. These trends can be related to a change in the electronic and structural properties, e.g. a varying magnitude of the rhombohedral distortion.

[1] D. Lencer et al., Nature Materials 7, 972 (2008)